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/* Copyright (C) 1994,1996,1997,1998,1999,2001,2002
Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <alloca.h>
#include <sys/poll.h>
#include <sys/types.h>
#include <errno.h>
#include <string.h>
#include <sys/time.h>
#include <sys/param.h>
#include <unistd.h>
/* Poll the file descriptors described by the NFDS structures starting at
FDS. If TIMEOUT is nonzero and not -1, allow TIMEOUT milliseconds for
an event to occur; if TIMEOUT is -1, block until an event occurs.
Returns the number of file descriptors with events, zero if timed out,
or -1 for errors. */
int
__poll (fds, nfds, timeout)
struct pollfd *fds;
nfds_t nfds;
int timeout;
{
static int max_fd_size;
struct timeval tv;
fd_set *rset, *wset, *xset;
struct pollfd *f;
int ready;
int maxfd = 0;
int bytes;
if (!max_fd_size)
max_fd_size = __getdtablesize ();
bytes = howmany (max_fd_size, __NFDBITS);
rset = alloca (bytes);
wset = alloca (bytes);
xset = alloca (bytes);
/* We can't call FD_ZERO, since FD_ZERO only works with sets
of exactly __FD_SETSIZE size. */
__bzero (rset, bytes);
__bzero (wset, bytes);
__bzero (xset, bytes);
for (f = fds; f < &fds[nfds]; ++f)
{
f->revents = 0;
if (f->fd >= 0)
{
if (f->fd >= max_fd_size)
{
/* The user provides a file descriptor number which is higher
than the maximum we got from the `getdtablesize' call.
Maybe this is ok so enlarge the arrays. */
fd_set *nrset, *nwset, *nxset;
int nbytes;
max_fd_size = roundup (f->fd, __NFDBITS);
nbytes = howmany (max_fd_size, __NFDBITS);
nrset = alloca (nbytes);
nwset = alloca (nbytes);
nxset = alloca (nbytes);
__bzero ((char *) nrset + bytes, nbytes - bytes);
__bzero ((char *) nwset + bytes, nbytes - bytes);
__bzero ((char *) nxset + bytes, nbytes - bytes);
rset = memcpy (nrset, rset, bytes);
wset = memcpy (nwset, wset, bytes);
xset = memcpy (nxset, xset, bytes);
bytes = nbytes;
}
if (f->events & POLLIN)
FD_SET (f->fd, rset);
if (f->events & POLLOUT)
FD_SET (f->fd, wset);
if (f->events & POLLPRI)
FD_SET (f->fd, xset);
if (f->fd > maxfd && (f->events & (POLLIN|POLLOUT|POLLPRI)))
maxfd = f->fd;
}
}
tv.tv_sec = timeout / 1000;
tv.tv_usec = (timeout % 1000) * 1000;
while (1)
{
ready = __select (maxfd + 1, rset, wset, xset,
timeout == -1 ? NULL : &tv);
/* It might be that one or more of the file descriptors is invalid.
We now try to find and mark them and then try again. */
if (ready == -1 && errno == EBADF)
{
fd_set *sngl_rset = alloca (bytes);
fd_set *sngl_wset = alloca (bytes);
fd_set *sngl_xset = alloca (bytes);
struct timeval sngl_tv;
/* Clear the original set. */
__bzero (rset, bytes);
__bzero (wset, bytes);
__bzero (xset, bytes);
/* This means we don't wait for input. */
sngl_tv.tv_sec = 0;
sngl_tv.tv_usec = 0;
maxfd = -1;
/* Reset the return value. */
ready = 0;
for (f = fds; f < &fds[nfds]; ++f)
if (f->fd != -1 && (f->events & (POLLIN|POLLOUT|POLLPRI))
&& (f->revents & POLLNVAL) == 0)
{
int n;
__bzero (sngl_rset, bytes);
__bzero (sngl_wset, bytes);
__bzero (sngl_xset, bytes);
if (f->events & POLLIN)
FD_SET (f->fd, sngl_rset);
if (f->events & POLLOUT)
FD_SET (f->fd, sngl_wset);
if (f->events & POLLPRI)
FD_SET (f->fd, sngl_xset);
n = __select (f->fd + 1, sngl_rset, sngl_wset, sngl_xset,
&sngl_tv);
if (n != -1)
{
/* This descriptor is ok. */
if (f->events & POLLIN)
FD_SET (f->fd, rset);
if (f->events & POLLOUT)
FD_SET (f->fd, wset);
if (f->events & POLLPRI)
FD_SET (f->fd, xset);
if (f->fd > maxfd)
maxfd = f->fd;
if (n > 0)
/* Count it as being available. */
++ready;
}
else if (errno == EBADF)
f->revents |= POLLNVAL;
}
/* Try again. */
continue;
}
break;
}
if (ready > 0)
for (f = fds; f < &fds[nfds]; ++f)
{
if (f->fd >= 0)
{
if (FD_ISSET (f->fd, rset))
f->revents |= POLLIN;
if (FD_ISSET (f->fd, wset))
f->revents |= POLLOUT;
if (FD_ISSET (f->fd, xset))
f->revents |= POLLPRI;
}
}
return ready;
}
#ifndef __poll
libc_hidden_def (__poll)
weak_alias (__poll, poll)
#endif
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